What's nice about this poll is that it starts to filter out the effects of high name recognition. I wasn't able to find how ABC's pollsters define "likely voters", but usually it's voters who have voted in the past two or three election cycles.

It would thus be logical that engaged voters are paying more attention to the election than those who don't make a regular habit of voting. And with that crowd, Lieberman's otherwise big lead is erased.

What does this poll tell us? That we have a four-way tie between Lieberman, Dean, Kerry and Gephardt. It tells us that Clark will probably bridge the difference between the four leaders and the also-rans.

And it tells us absolutely nothing else, since it's the state polls that truly matter.

The poll is the first of the season by pollster PMR, so we have no trend lines. But it is important for one particular reason -- it seeks to poll only those who are "very likely" to attend the caucuses. Most Iowa polls fail to implement this key filter.

Caucuses are not like primaries. It requires a far greater degree of commitment than simply entering a voting booth and pulling a lever (or touching a computer screen). Thus, polls that identify caucus goers are theoretically more salient than those that simply poll regular Iowa Democrats.